Study on the Adsorption Properties of Different Binary Hydrotalcite for Fluoride Ions in Water
Fluorine pollution is currently a global problem,and layered double hydroxides(LDHs)have great potential in ad-sorbing anions.In order to screen for cations with good fluoride removal ability,this study investigated the influence of differ-ent cations on the fluoride removal ability of synthesized nitrate based LDHs structures.Different types of LDHs(Ca-Al,Mg-Al,Mg-Fe,Ca-Fe)were prepared by hydrothermal method.XRD,FT-IR,BET,SEM and other testing methods were used to characterize the LDHs,the adsorption performance and mechanism of the LDHs materials were compared through F-adsorp-tion experiments.The results show that Ca/Al-LDHs,Mg/Al-LDHs,and Mg/Fe-LDHs all exhibit the nitrate intercalated LDHs diffraction peaks and microporous mesoporous structures,exhibiting a sheet-like stacking structure with specific sur-face areas of 7.658 2,2.923 9,and 13.200 3 m2/g,respectively.However,Ca/Fe-LDHs are difficult to prepare LDHs materials through hydrothermal reactions.The Ca/Al-LDHs in the prepared hydrotalcite exhibit better overall fluoride removal perfor-mance.At a F concentration of 10g/L,the adsorption rate can still be maintained at around 95％at 20 ℃ to 40 ℃,with a maxi-mum adsorption capacity of 240.35 mg/g.The process of adsorbing F conforms to the quasi second order kinetic model,Ca/Al-LDHs conforms to the Langmuir adsorption isotherm model,while Mg/Al-LDHs and Mg/Fe-LDHs are more in line with the Freundlich adsorption isotherm model.This study shows that Ca/Al-LDHs had strong fluorine removal potential.
layered double hydroxidesadsorptionhydrothermal synthesisfluoride ion
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